The present invention relates to a device for the shearing of wood logs to obtain low-thickness sheets, by means of curved cutting paths, with curvature radius fully adjustable and variable during the entire operation, in accordance with the shearing process described in co-pending U.S. patent application Ser. No. 073,112 filed on Sept. 6, 1979.
Two devices are currently used to obtain thin wood sheets, called "veneers or shearings" a reciprocating-motion plane shearer and a rotating-motion stripper.
Normally, a reciprocating-motion plane shearer is composed of a structure supporting and blocking the wooden log, and of a supporting structure for the cutting tools, i.e., the blade or cutter and a pressure bar.
Such structures have a linear reciprocating motion, relative to each other, in a direction that may be horizontal or vertical or tilted.
The so-called horizontal shearers usually include a tool-carrying device operative to reciprocate with a horizontal motion, and a log-carrying device operable to move in an intermittent, straight-line advancing motion, at right angles to the motion of the tool-carrying devices and synchronized therewith, to obtain a definite-thickness at every back-and-forth motion of the tools. Generally, in the so-called vertical shearers, the device equipped with reciprocating vertical straight-line motion is the log-carrying device, whilst the tool-carrying device shifts with an intermittent straight-line motion at right angles to the motion of the log-carrying device.
A rotating-motion stripper is normally composed of a device supporting and blocking the log, which rotates on a fixed axis and a cutting-tool supporting device, for supporting a blade and pressure bar, having a continuous radial straight-line advancement motion towards the rotation axis of the log-carrying device.
The operation by which a definite-thickness thin sheet of wood is obtained at every turn of the stripper is known as "eccentric stripping", for in such cases the log-carrying device is built in such a way that the log rotates eccentrically around the rotation axis, having contact with the cutting tools getting continuously closer to the axis itself at a speed which is proportional to the speed of rotation.
A plane shearer with reciprocating motion does not always cut the sheets on a plane, while a rotating-motion stripper cuts the sheets with continually decreasing-curvature paths according to a spiral shape whose parameters are not variable as wanted in every.